1. Field of the Invention
The present invention relates generally to packaging systems, and more particularly, to a stack loading apparatus capable of receiving, aligning, and delivering a stack of sheet-like objects to a package.
2. Description of the Related Art
Pre-sliced luncheon meat, such as bologna, salami, and ham, is often packaged in pre-fabricated rigid plastic containers which conform to the shape of the meat slices. These plastic containers allow the consumer to remove a few slices of meat at one time while providing a convenient container for storage of the remaining slices.
At the processing plant, the meat is usually vacuum packed in the plastic containers to prevent spoilage during distribution. Vacuum packing causes the plastic containers to collapse a small amount and to surround the stacks of meat slices very tightly. In order for the containers to retain their shape after the package is opened and the vacuum is broken, there must be a low tolerance between the walls of the plastic container and the meat. The use of containers with low tolerance requires that the meat slices be accurately cut, stacked, and concentrically aligned so that the stack of meat slices will fit into the plastic container.
Luncheon meat is usually sliced by feeding long "logs" of meat into a slicing machine which produces unaligned stacks of slices. In certain automated meat-packaging facilities, the unaligned meat stacks exit from the slicing machine via an output conveyer belt. Assembly line workers then manually remove the unaligned stacks from the output conveyer belt and align each stack of meat slices with their fingers so that the stack will fit into the rigid plastic containers. The workers then press the stack into the containers by hand.
The use of assembly line workers to manually package stacks of meat slices has many disadvantages. Because the slicer machine conveyer belt moves continuously, the workers must align each stack of meat very quickly. This fast pace and the repetitive motion causes the work to be tedious. This can result in the stacks not being aligned in a uniform manner. Non-uniform stacks will not fit properly into the low tolerance containers.
The tedious nature of the work also creates a need for the workers to take several rest breaks during their work shift. The rest breaks are necessary because the stacking/packing work requires long periods of repetitive limited movements of the workers' muscles. The workers must have a few minutes to relax; otherwise, their muscles will become strained. These rest breaks slow production and reduce yield.
Other events also reduce yield. If a worker spends too much time aligning any one particular stack, the slicing machine may have to be stopped in order for the worker to "catch up." This also slows production and frustrates the worker.
Thus, there exists a need for an apparatus which can receive an unaligned stack of meat slices, align the stack, and deliver the stack to a container.